1. Field of the Invention
The present invention relates to an image processing apparatus, an image processing method, and a program therefor. More particularly, the present invention relates to an image processing apparatus, an image processing method, and a program whereby a three-dimensional display is expressed by means of either a space-division or time-division format.
In further detail, the present invention relates to an image processing apparatus, an image processing method, and a program whereby input images are determined to be data in space-division format or time-division format, and then converted into images in an output format.
2. Description of the Related Art
In motion image media such as television and movies, image data is typically displayed on a flat plane. For this reason, even if a person views the displayed images, that person does not perceive depth information related to the images. Although it has been long established that the use of the stereoscopic principle can cause a viewer to perceive depth even when displaying image data on a flat plane, broad adoption of such techniques has not occurred.
Meanwhile, 3D televisions with built-in mechanisms enabling stereoscopy are starting to be actually sold as commercial products, while three-dimensional image broadcast tests using normal broadcast networks have also begun. Furthermore, the number of movie theaters adapted to screen 3D movies is also notably increasing. Environments for viewing 3D images are rapidly becoming more available.
In stereoscopy, images captured from different perspectives are respectively presented to a person's left and right eyes. Depth is then perceived from the parallax between the left and right images, or the perception of depth is induced by convergence. As a result, a person can perceive depth, even when given image data displayed on a flat plane. Technology of the related art associated with three-dimensional image display processing is disclosed in Japanese Unexamined Patent Application Publication Nos. H9-107562, H8-30806, H10-51812, 2000-209614, 2005-151534, and H6-194602, for example.
In stereoscopy, a large number of methods for respectively presenting different images to the left and rights eyes have been proposed, and most can be mainly categorized into one of two types of methods: a method wherein the different images to be respectively presented to the left and right eyes (hereinafter, the image to be presented to only the left eye may also be referred to as the left image, while the image to be presented to only the right eye may also be referred to as the right image) are presented in alternation (i.e., a time-division format), and a method wherein a single frame is constructed from the left image and the right image and then presented (i.e., a space-division format).
When presenting images in either of the above formats, some kind of differing modulation is applied to the left and right images, such that only the left image is incident on the left eye, and only the right image is incident on the right eye. Hereinafter, examples of three-dimensional image display systems currently in practical use (or currently being developed for practical use) will be given for each of the above formats.
[1. Space-Division by Circularly-Polarized Light]
First, space-division by circularly-polarized light will be described. This method assumes a progressive display format, wherein a single frame is divided into odd fields (i.e., odd lines) and even fields (i.e., even lines), with the left image being displayed in the even fields and the right image being displayed in the odd.fields (the reverse is also possible). The light from each field is polarized differently by a polarizing filter applied to the display face. For example, by applying different circularly-polarizing filters alternating every line, the even field light can become right-polarized light, while the odd field light can become left-polarized light. By wearing glasses to which different polarizing filters have been applied on the left and right sides thereof, the viewer perceives only the left image with the left eye, and only the right image with the right eye.
Three-dimensional broadcast tests using the above display format has actually begun on satellite broadcast channels, and the commercial release of a large flat-panel display compatible with such broadcasts is also planned.
[2. Time-Division by Liquid Crystal Shutter Glasses]
Next, time-division by liquid crystal shutter glasses will be described. In a time-division format using liquid crystal shutter glasses, left images are displayed as even-numbered frames (or fields, in the case of interlaced display), in alternation with right images displayed as odd-numbered frames, for example. The viewer puts on liquid crystal shutter glasses and views the images. The liquid crystal shutter glasses are synchronized with the alternating presentation of left and right images, and alternately block incoming light at the viewer's left or right eye. This behavior causes only left images to be incident on the left eye and only right images to be incident on the right eye. Thus, by the stereoscopic principle, the viewer is able to perceive a three-dimensional image.
Formats using liquid crystal shutter glasses have been in use for a long time, and liquid crystal shutter glasses and a wide variety of products are currently being sold.
[3. Time-Division Using Polarized Light]
Next, time-division using polarized light will be described. In many cases, the liquid crystal shutter glasses used in the above time-division format 2 are expensive. Consequently, time-division is realized using polarized glasses, which are cheaper compared to liquid crystal shutter glasses.
The present format is basically a time-division format, and thus the construction of frames for display does not differ from the time-division method using liquid crystal shutter glasses. In other words, left images are displayed in even frames, and right images and displayed in odd frames, for example. The present format differs from the above time-division format 2 in that a circularly-polarizing filter is installed in front of the image display unit. The polarizing filter is made up of a liquid crystal panel, and is able to change polarization with time. Thus, by changing the polarization direction every frame, it becomes possible to convert only the left images displayed in even frames to left-polarized light, and convert only right images displayed in odd frames to right-polarized light, for example. Similarly to the space-division by circularly-polarized light in the above format 1, the viewer puts on polarized glasses with different polarizations on the left and right sides thereof. The polarized glasses cause only left images to be incident on the left eye, and only right images to be incident on the right eye, thereby enabling the viewer to perceive a three-dimensional image. A movie theater system wherein a polarizing liquid crystal panel is installed in front of a projector is currently being sold by the RealD corporation.